Machine for inspecting involute curves



Aug. 14,1928. 1,680,563

E. W. MILLER MACHINE FORINSP-ECTING INVOLUTE CURVES Filed March 21, 1927 2 Sheets-Sheet 2 ia W47 i %WW I Patented Aug. 14, 1928.

UNITED STATES 1,680,563 PATENT oFF cE.

nnwnnn w. MILLER, 01? SPRINGFIELD, vnnmpm, ASSIGNOR To run FELLOWS ens-n swan oommmr, or SPRINGFIELD, VERMONT, A CORPORATION or VERMONT.

MACHINE FORINSPECTING INVOLUTE CURVES.

Application filed March 21, 1927. Serial no. 177,001.

This invention *relates to machines for inspecting and testing the accuracy of 1nvolute curves, Including the faces of gear teethygear shaper cutters, formers or cams "than any -heretofore made. This objecthas been accomplished by, and the invention consists in, new features of construction by which possible causes of error have been eliminated and measurements of grcater'refincinent and in smaller units have been achieved, as described in detail in the following specification.

For convenience of description, I will assame that the machine herein illustrated and described is designed for inspecting the involute curves of spur gear wheels and'pinions; making it understood, however, that this assumption is not to be construed as in scale;

any sense a limitation as to the forms and articles which may be inspected by the use of the machine, or of the scope of the appended claims.

In the drawings,-'- j Fig. 1 is a front elevation of an inspecting machine for the purpose set forth, embodying this invention; I

Fig. 2 is a plan'view of the machine with parts represented as cut away and shown in section on line 2-2 of Fig.1;

Fig. 3 is a vertical section on line'33 of Fig. 2; v

Fig. 4 is a vertical section on line .4-4 ofFig. 2; f

Figs. 5 and'6 are fragmentary sectional views taken on lines 55 and 66, respectively, of Fig. 3, and shown on a larger Fig. 7 is a front elevation and partial section showing the contact member or feeler of the machine and parts adjacent thereto;

Like reference characters designate the same parts wherever they occur in all the figures. v

In its general principles, this machine is the same as those illustrated in the prior patents of E. R. Fellows for involute measuring machine, granted November 9, 1926, numbered 1,606,353 and 1,606,520, respectively; and in many of its details it is similar in construction to said machines. It includes a rigid and massive base 10 having parallel bars or tracks 11 and 12, the u per surfaces of which are in the same pfime, preferably in a horizontal plane, and establish the rolling plane of the machine. A rolling head consisting of an arbor 13 and a massive disk 14 secured to said arbor, and rolling cyhnders 15 and 16 either mounted upon or integral with the arbor, rests on the track ways and is adapted to roll thereon. The arbor has an extension 17 adapted to receive the gear 18 or other form to be tested and to which the latter is secured by a clamp .screw'19. The supporting surfaces of the track ways 11 and 12 are ground and'lapped with the greatest practicable accuracy to true planes and the rolling cylinders 15 and 16 are similarly ground and -lapped to true cylinders having the same diameter as the base circle of the involute curve to be tested. Between the track ways, the base is open or recessed to admit the lower part ofthe disk 14, and the latter is substantially narrower than the s ace between the track ways, and the parts 0 the base on which the lat-' ter are supported, in. order to avoid any contact therewith of the disk, to the end that there may be no displacement or impedance of the, rolling head due to .such contact and to the dragging efi'ect resulting therefrom.

A stop 20 is mounted on the base at one side of the rolling head and has a beveled or V-sha'ped end projecting towardthe latter and adapted to enter a complement'al groove 21 in the periphery of the disk 14 arranged in a plane perpendicular to the axis of the arbor; This stop is adjustable -lengthwise, for which purpose it is located Adjusting nuts 25 arethreaded on this stud and embrace the ear. 7 A complemetal alining plun'ger26, likewise formed with a beveled end adapted to enter the groove 21 is mounted in a guideway at the opposite side of the rolling head, in line with the stop 20, and is provided with rack teeth 27 meshing with a pinion 28 on a shaft 29, having its bearing in the base, and to which are connected a crank 30 and a weighted arm 31. The plunger 26 may be advanced to enter the groove 24 when the rolling head is engaged with the stop 20; and said stop and plunger are so arranged with respect to the rolling head and the groove 21, that when they are both entered in the groove and in contact with the beveled sides thereof, they will locate the rolling head with its axis erpendieular to the track ways and the '51: between the track ways and out of contact with either. This position of the head I have designated by the term radial position. It should be brought into this position at frequent intervals in the use of the machine by operation of the plunger as above described. U on release 0 the crank after its mani u ation for this purpose, the plunger is withdrawn by the weighted arm 31 to a position far enough removed from the rolling head to permit rolling movement thereof through the distance necessary for inspection of the curved form for which the machine is adapted.

A contact member or feeler 32 bears on the side of the tooth bein inspected, and is moved thereby in one irection, or permitted to move in the oppositedirection, by any departure of the tooth face from the true involute curve. This contact member is carried by an arm or lever 33 supported by point hearings in a manner which eliminates all looseness and prevents any movement of the arm except oscillative movement about a given axial line. These point bearings are provided by the upper extremities of cone which fit close y in passageways in a housing iece 36, wherein they are secured adjusta ly by screw threaded portions 37 and lock nuts 38. The pointed ends of the pins extend into alined V grooves 39 and 40 in a bar 41 which passes through the arm or lever 33 and is secured thereto. The bottoms of these V grooves establish the pivot axis of the arm 33, which is perpendicular to the arm. That portion of the arm which embraces the bar 41 consists of alined but separated sleeves of substantial length, suffieient to give an extended connection and firm grip with the bar. The bearing points contact with the bottoms or inner extremities of-the grooves 39 and 40 only, whereby they provide a substantially frictionless hearing without looseness.

Contact between the bearing points and the bar is assured by a spring impelled pointed in 42 which presses downward on the axle bar 41 between (preferably midway between) the supports 34 and 35, and is carried by a plunger 43 fitted slidingly and keyed in a guideway 44 in the housing piece 36, and having a protruding end 45 carrying an adjustable abutment nut 46, between which and a plate 47 bridging the open end of the guideway, a spring 48 is confined. The plunger 43 has an aperture 49 through which the axle bar 41 passes, and the pin 42 is passed through a passageway in the upper end of the plunger and secured thereointed pins or bars 34, 35,.

34 and 35 enables their points to be brou ht in the same horizontal plane, while the 5 iding mount for the pin 42, and its spring actuation, causes it to assume the only position permitted by the bar 41, that is, one in the axial line of the feeler arm. The center lines of the pins 34, 35 and 42, including their pointed extremities, and of the plunger 43 are all in the same plane, whereby the alinement of the pin polnts is maintained however they may be adjusted. It.

will be seen that the pin 42 applies in a frictionless, non-slipping way, a load of constant value ensuring contact of the supportin points with the axle bar 41 in the axial 11118 of the latter and preventing displacement of the arm 33 in any other manner except singularly about this axis.

The arm or lever 33 carries a finger 51 beside the contact point or feeler 32, and as near the extremity of the latter as it can feasibly be brought without interference with the object to be tested, which finger bears on the plunger 53 of a measuring instrument 54, said plunger being pressed outward by a spring and thereby maintained in firm contact with the finger 51 and caused to follow the withdrawing movements of the latter, while also causing the contact point to bear and press against the side of the tooth under inspection.

The measuring instrument here shown is equipped with an indicator 55 cooperating wlth a dial or scale 56. This particular instrument is one which can be purchased in the open market and gives accurate indications in terms of ten-thousandths of an inch and fractions thereof. As the indicator in itself is not my own invention, I have not illustrated its operating parts and mechanism herein; and from the point of view of my actual invention, the terms or units in which the readings of the indicator are given are of minor importance. What is of particular importance is that I have eliminated causes of error heretofore existing in the mechanism between the object being tested and the ultimate indicator, by elimimating multiplying levers, sliding pivots and possible dragging of the rolling head or unit, and by providing positive means for centering or alining the rolling head so that it will roll in the prescribed path and its axis during rolling will always be exactly parallel to a given straight line in all of its positions. Thus the gear or cutter to be inspected is rolled truly and correctly on its base circle, and the movements given to the contact point or feeler by curved forms which are not true involutes are transmitted to the indicator without error due to looseness of-"pivots, elastic distortion of the transmitting parts, or frictional resistance.

tating therein.

The housing piece 36 not only provides the supports and guides for the bearing pins 34, 35, and plunger 43, but it also embraces and protects the feeler lever 33 and supports the indicator instrument 54. For this purpose it is formed with a protuberant enveloping portion 57 which embraces the major part of the feeler lever, and with wings 58 which are adapted to bear against the outer face of the base and are secured thereto, one or both of which has at its upper end provisions for mounting the indicator instrument. Stop screws 59 are set in opposite sides of the enveloping portion 57 and are fitted with lock nuts 60. They project inward at opposite sides of the feeler lever and their functionis to obstruct said lever, preventing it from movement and thereby guarding it from injury, when in shipment. The contact point or feeler 32 is adjustable with respect to its carrying arm or lever 33, having a shank 61 which is entered into a socket in the upper part of the lever and restson an adjusting wedge 62.- The latter occupies a transverse passage in the lever and is keyed so as to be incapable of ro- It has an inclined surface on which the shank of the contact feeler rests. Its ends protrude from the lever and are threaded, carrying adjusting nuts 63. This adjustment is used to bring the point of the feeler which engages the gear tooth in course of inspection exactly in the rolling plane. When once adjusted, the feeler is secured by a suitable clamp, one embodiment of which is a shoe fitting against the side of the shank 61 and pressed against it by a screw 64.

" Preferably 'the rolling head is provided with'a scale 65 on one side of the disk 14 to .indicate the extent of its angular movement holder has a shank or stem contained in a socket in the base and held therein by a clamp screw 69; these clamp screws permitting a wide range of adjustment in the index.

In using the machine for its intended purpose, the contact feeler and the axis of the rolling head are first brought into the radial position, that is, the position in which this axis, the contact point of the feeler, and the axis of the feeler lever, are all in the same plane perpendicular to the rolling plane. This is done with the aid of a suit: able gage with which the machine is provided, and the stop 20 is adjusted, if necessary, to bear in the groove of the rolling head and establish a limit and a starting point for subsequent rolling actions. The contact point is then adjusted to the correct height, that is, the position where its point of engagement with the tooth of the gear form being tested is in the rolling plane, or plane of the supporting surfaces of the track ways. Such adjustment is effected by' the adjusting wedge 62 with the aid of a master form applied to the arbor of the rolling head in the same position which is occupied by the gear being tested, and having a surface to contact with the feeler. Such master form has a surface crossing the rolling plane, the relationship of which to the involute curve is exactly known, so that when this surface is rolled past the feeler, the displacements thereof, if any, show the adjustment necessary to be given to it in order to bring it into the rolling plane.

When so adjusted, the machine is in order for testing or inspecting gear teeth and the like, which is done by securing the gear on the arbor with its tooth face to be inspected in contact with the feeler while the rolling head is against the stop 20, and then rolling the head to the left. Preferably the disk 14 is made slightly out of balance and is placed with its center of gravity at the left of its axis, whereby it has a constant tendency to roll to the left. After testing each tooth the gear is adjusted on the arbor to bring another tooth into position, and the process is repeated. At suitable intervals, the plunger 26 is brought forward while the rolling head is against the stop 20 to center and aline the rolling head as before described.

What I claim and desire to secure by Letters Patent is:

1. A testing machine of the charatcer described, comprising a base having means establishing a rolling plane, a head adapted to roll on said plane, a feeler, arranged'to bear on the face of a tooth of a gear carried by the head, an indicator engaged with said feeler for operation by movement thereof in said plane, and means for locating said rolling head clear of all parts of said base comprisin faces adapted to roll .on said tracks, and an intermediate massive disk extendin into the space between the tracks, said dis having an encircling peripheral roove, asto mounted on the base arrange to enter sai groove when the head is at one extreme position and a plunger at the op site s1de of the base adapted to be projecte into the said groove at the same time, said disk being narrower than the space between the tracks,

and said stop, plunger and groove bein so disposed that when both the stop and p unger are entered in the groove theywill locate the disk clear of both tracks.

4. A machine of the character described, a base having separated tracks side by si e with supporting surfaces in the same plane, a rolling head having cylindrical surfaces adapted to rest and roll on the supporting surfaces of said tracks, said rolling head having also a massive disk narrower than the space between said tracks and extending partially into said space, said disk having also an encircling peripheral groove in a plane perpendicular to the axis of the head, with converging sides, and stops mounted on the base at opposite sides of the axis of the head adapted to enter said groove and engage the converging sides thereof, one of said stops being a plunger movable toward and away from the disk.

5. A machine of the character described,

comprising a base having separated tracks side by side with supporting surfaces in the same plane, a rolling head having cylindrical surfaces adapted to rest and roll on the supporting surfaces of said tracks, said rolling head having also a massive disk narrower than the space between said tracks and extending partially into said space, said disk having also an encircling peripheral groove in a plane perpendicular to the axis of the head, with converging sides, and stops mounted on the base at opposite sides of the axis of the head adapted to enter said groove and engage the converging sides thereof, one of said stops being a plunger movable toward and away from the disk, having a series of teeth, and means for so moving said plunger consisting of a pinion meshing with said teeth and an arm for turning said pinion.

'6. A machine of .the character set forth having a base and a rolling head mounted to roll on the base, a stop and a cooperating plunger for locating the rolling head in a prescribed position on the base, a shaft geared to said plunger for moving it, a crank connected to said shaft for applying rotatory movement thereto, and a weighted arm secured to said shaft normally placing and holding the same in a position causing refiracion of the plunger from the rolling 7. A machine of the character and for the purpose set forth, comprisin a base havmg supporting means establis ing a rolling plane, a rolling head adapted to ca the piece to be tested and having cylin rical surfaces resting and adapted to roll on said supporting means, a feeler lever, separated point bearings onwhich said lever rests, said point bearings being in a line parallel to the rolling plane and establishing a frictionless non-shding pivot support, a feeler carried by said lever adapted to make contact with the article being tested, and an indicator operable by movements of said lever.

8. In a machine of the character described, a base, a lever, supporting means for the lever on said base engaging the lever in a frictionless manner at the pivot axis thereof, and a feeler or contact member carried by said lever and being adjustable thereon toward and away from said pivot support.

9. In a machine of the character described, a feeler device comprising a feeler or contact member, a lever having a socket in which said member is located, an adjusting wedge mounted in said lever and being shiftable therein across said socket, and on which the feeler member bears, adjustment of said wedge causing the feeler point to be projected more or less from the end of the lever, and pointed supports providing a frictionless non-sliding pivot bearing for said lever.

10. In a machine of the character described, a pivoted feeler lever, separated point bearings for said lever, a pivot bar secured to said lever having grooves with converging sides, the bottoms of which receive and rest on said point bearings and an indicator having engagement with said lever at a distance from said bearin 11. In a machine of the c aracter described, a feeler lever and means for supporting the same in a frictionless non-sliding manner, comprising a bar secured to said lever and extending perpendicularly thereof, said bar havin in se arated parts alined grooves in one si e an in an intermediate part a recessed surface at the opposite side, the bottoms of said grooves and said reccssed surface being all in the same line, a supporting structure having three passages, all in the same plane, bearing pins fixed in the two outermost of said passages having pointed ends entering the said grooves, a plunger slidingly mounted in the intermediate one of sald passages embracing said pivot bar and having a bearing point engaging said recessed surface, and a spring acting on said plunger forcing said bearing point against said surface and said bar against the before named pins.

12. In a machine of the character described, a sup orting structure, pointed ins mounted in said structure located with their points clear thereof, a lever having a pivot bar with recesses receiving the points of said pins and resting thereon, a plunger slidingly mounted in said supporting structure between said pins, said plunger embracing the said pivot bar and having a pointed pin projecting oppositely to the first named pins engaging said pivot bar in line with the extremities of-the first named pins, and a spring on said plunger to press the pin thereof against said pivot bar.

13. In a machine of the character described, a feeler lever separated point support-s forming a frictionless non-sliding bearing on which said lever rests, and an intermediate load-applying point exerting force on said lever toward the first named points, all of said points being in the same straight line.

14. A machine of the character described comprising a base having tracks with supporting surfaces in the same plane, a rolling head having cylindrical surfaces adapted to roll on said tracks, a feeler lever having a contact point in said rolling plane, means supporting said lever for frictionless pivotal movement about an axis distant from said plane, an indicator engaged with said lever at a point distant from said pivot axis for indicating movements of the lever about said axis, and means for positioning said rollin head with its axis parallel to the axis 0 said lever.

15. A machine of the character described having plane surface supporting means, a

rolling head having a cy indricalsurface making rolling contact with said supporting means and adapted to carry the articles to be tested, a pivotally mounted feeler having its axis parallel to said plane and at a substantial distance therefrom, a stop for locating said rolling head in a position where its axis is in the plane, perpendicular to the rolling plane, which passes through the feeler lever axis, said head being Weighted in a manner tending to cause it to roll away from said stop, and an indicator for measuring movements of said feeler lever.

17. In a machine of the character described, a base, a feeler lever, a pivot support for the lever on the base, and a load-applying means, both said support and loadapplying means engaging said lever in the pivot axis thereof.

In testimony whereof I have aflixed my signature.

EDWARD W. MILLER. 

